Nothing in this psalm is about Chanukah. Why do we say it here?
You are right. The psalm has no Greeks, no Temple and no oil. Several classic commentators read it as being about the Exodus and the early years of the Jewish people. Rashi says verse 4 is about Shabbat, the festivals and the commandments that tell us to remember Egypt. Metzudat David (a line-by-line commentary from the 1700s) says the "food" in verse 5 is the manna.
The custom is not the same everywhere. The Ashkenaz siddur on Sefaria has only the blessings, HaNerot Halalu ("These lights," said after lighting) and Maoz Tzur at the menorah. The Sephardic siddur Edot HaMizrach adds Tehillim 30, the verse Vihi Noam and Tehillim 91. Siddur Sefard has Tehillim 30, this psalm, 112, Vihi Noam, 91 and 67. The Shulchan Aruch (the main code of Jewish law) lists only HaNerot Halalu after lighting. The Kaf HaChaim (a Sephardic law commentary from the early 1900s) adds Tehillim 30 and 67. We could not find an early source for who added this psalm, or why.
What the words do give is a bridge. The Gemara says Chanukah was set "with praise and thanks," and the psalm opens with praise and thanks. The Meiri says the psalm is about faith that God can change nature, and hope that does not give up in a long exile. And verse 4 speaks of a "reminder" of God's wonders, which is the next question.
So the psalm was not written for Chanukah. It was placed beside the lights by custom, and the links we found come from its words, not its story.
Rashi and Metzudat David on Tehillim 111:4-5,Siddur Sefard, Siddur Edot HaMizrach and Siddur Ashkenaz, Chanukah,Shulchan Aruch, Orach Chaim 676:4,Kaf HaChaim, Orach Chaim 676:30,Shabbat 21b,Meiri on Tehillim 111:1God "made a reminder" of His wonders. Isn't a reminder something people make?
Usually it is. We build a monument or mark a date after something happens. Verse 4 says it the other way: "He made a reminder of His wonders." God is the one who makes it.
Rashi says the reminder is the calendar and the commandments. God set Shabbat, the festivals and the commandments, about which it says, "And remember that you were in Egypt." Metzudat David points to a jar. After the manna fell, Moshe told Aharon to set a jar of it before God, to be kept "for your generations" (Shemot 16:33).
Ibn Ezra (a Spanish commentator who died in the 1160s) reads it differently. In every generation, he says, God makes a reminder of the wonders He did in Egypt, because He is gracious to those who cry out to Him. Radak (Rabbi David Kimchi of southern France, who died in 1235) spells it out as one option: the wonders God does in every generation are a reminder of the first ones in Egypt.
Now add Chanukah. The Gemara says the rabbis set the days "the next year." The Bnei Yissaschar (a Chassidic book by Rabbi Tzvi Elimelech of Dinov, who died in 1841) asks why they waited. His answer: some miracles come once and are gone. Others are a light that comes back every year on the same date. The rabbis could not tell which kind this was. A year later, through holy inspiration, they knew that the light had returned, and only then made the days a holiday. So for him, God's "reminder" is a wonder made to keep giving.
That makes four readings. For Rashi the reminder is the commandments. For Metzudat David it is the jar of manna. For Ibn Ezra, and for one option in Radak, it is the later rescues. For the Bnei Yissaschar it is a wonder that returns. The last is a Chassidic reading, not the plain meaning. The psalm does not choose between them.
Rashi on Tehillim 111:4,Metzudat David on Tehillim 111:4,Shemot 16:33,Ibn Ezra on Tehillim 111:4,Radak on Tehillim 111:4,Shabbat 21b,Bnei Yissaschar, Kislev and Tevet, Essay 4, section 81Verse 6 says God gave His people "the inheritance of the nations." Isn't that conquest?
The verse says: "He told His people the power of His works, to give them the inheritance of the nations." Read plainly, it is about the Jewish people taking land from other peoples. A skeptic will say that is what every conqueror claims.
Rashi knew the objection. His first comment on the Torah, on Bereishit 1:1, quotes Rabbi Yitzchak, who cites this verse, as he also does in Midrash Tanchuma (a collection of rabbinic teachings). The Torah opens with Creation, he says, so that if the nations tell Israel, "You are robbers, you conquered the land of seven nations," Israel can answer: the whole earth belongs to God. He made it and gave it to whoever seemed right to Him. By His will He gave it to them, and by His will He took it from them and gave it to us.
That answer is about who owns the land. The commentators on the psalm add one about fairness. Radak (Rabbi David Kimchi of southern France, who died in 1235) says what God did in those wars was not injustice but truth and justice. The earlier peoples had done evil, and the land is holy ground where such people could not stay. Metzudat David says they were driven out because of their sins.
The Torah adds a warning aimed at Israel. In Devarim 9:4-5 Moshe tells the people not to think, "It is because of my righteousness that Hashem brought me in to take this land." It is not, he says. It is because of the wickedness of those nations, and to keep the oath to Avraham, Yitzchak and Yaakov.
Radak also points to the word "told." God told them in advance, so no one could say it happened by chance. Those are the answers these sources give. They are about ownership and about the deeds of the earlier peoples. A reader may still find the question open.
Tehillim 111:6,Rashi on Bereishit 1:1 and on Tehillim 111:6,Midrash Tanchuma (Buber edition), Bereishit 11,Radak on Tehillim 111:6-7,Metzudat David on Tehillim 111:7,Devarim 9:4-5